The present invention relates generally to tillage tools and, more specifically, to a knock-on sweep and structure for preventing the sweep from falling off the end of a shank.
Standard assemblies for implements such as chisel plows and field cultivators typically include a spring trip shank assembly extending downwardly to a tool-receiving end which mounts a shovel, point or sweep. Previously available mounting structure included bolts extending through holes in the tool and the shank to secure the tool. When the tool in such an assembly has to be replaced because of wear or damage, the bolts must be removed. Wear and corrosion of the bolts substantially hinders removal and often makes the replacement a difficult and time-consuming task.
Several solutions to the problem of easily and quickly replacing worn elements such as sweeps on shanks have been developed over the years, including adapter brackets providing a self-locking fit with a matching taper on knock-on sweeps. Frangible pins and bolts have also been suggested. However, most retaining devices have suffered from one or more problems, including need for additional parts and the loss of sweeps when encountering high removal forces during transport and during rebounding of the shank from a tripped position. To reduce incidences of sweeps falling off the shanks in quick mount arrangements, some manufacturers have offered detent mechanisms such as a retaining clip in the form of a sheet metal stamping with a spherical protrusion that fits into a hole in the sweep. To release the sweep, a screwdriver or other tool is used to depress the clip and move the protrusion away from the hole. Other detent arrangements are shown, for example, in U.S. Pat. Nos. 3,061,021 and 6,289,996. Such detents generally help retain the sweeps on the shanks, but the forces exerted on a sweep, particularly forces exerted on deep tillage tools, can be so great that the sweep fails to stay on the shank. The geometry of most previously available sweep detent arrangements, including non-symmetrical mating surfaces on some, usually limits penetration of the retaining surface into the hole so that retaining forces are limited. Some care must be taken to align the protrusion with the hole, and part tolerances, variations in force used to mount the sweep, or lack of indexing of the clip relative to the shank can make such alignment troublesome. A relatively small, ramped contact area between the clip and the hole also increases the potential for losing a sweep. Soil moving up and around the stem portion of the sweep can move the clip from the detent position or wear away the clip until it is ineffective for holding the sweep on the shank. Extreme forces on the detent, such as those which occur during rebound, can also cause deformation of the detent. If the detent deforms, loosened sweeps can unacceptably dangle from the shank or be lost. A hefty detent construction or frequent detent replacements are therefore usually required.
It is therefore an object of the present invention to provide an improved sweep retaining structure for a knock-on sweep that overcomes most or all of the above-mentioned problems. It is another object to provide such an improved sweep retaining structure which is simple and inexpensive to manufacture and assemble and yet reliably holds the sweep on the shank and facilitates quick and easy removal of the sweep. Further objects include providing an improved sweep and providing an improved retainer for use with such structure.
It is yet another object to provide an improved sweep retaining structure which provides reliable retention independently of manufacturing tolerances, forces applied during sweep mounting and precise alignment of mating portions of the sweep assembly. It is another object to provide such a structure having an improved and simplified retainer mounting arrangement. It is a further object to provide such a structure wherein the retainer is positioned for proper engagement with a contact area on the sweep without direct contact with a bolt or similar fastener. It is still another object to provide such a structure having support and guidance structure for the detent to facilitate alignment and prevent bending of the detent.
It is yet another object to provide an improved sweep retaining structure which eliminates need for flat retaining clips and which provides improved wear and retaining characteristics compared to at least most previously available clip type retaining structures. It is another object to provide such a sweep retaining structure with integral retainer guide and wear reducing structure for improving retention and preventing retainer deformation.
Sweep retaining structure constructed in accordance with the teachings of the present invention includes a retainer fabricated from wire spring material and including a bent wire base supported in a groove on the underside of the wedge support which mates with stem portion of the sweep. The wedge support is apertured, and a central curved portion of the retainer passes through the aperture and supports a sweep-contacting end above the surface of the wedge support. The end is biased toward a contact area on the sweep, preferably the top edge of a slot in the stem, to engage the area and eliminate sweep loss problems by preventing the sweep from slipping down away from the wedged mounted position. To remove the sweep, a tool is inserted through the slot to depress the retainer end, and the sweep is forced downwardly off the wedge support.
The retainer is simple, inexpensive and reliable. The groove support eliminates a separate retainer fastening bolt or contact with a fastening bolt and improves ease of assembly, proper positioning and wearability of the retainer. The retainer can be easily slipped into position on the wedge support.
The slot in the stem is preferably located near the top of the connecting portion and defines an end contact edge. To protect the edge and the end of the retainer from wear as well as prevent soil and debris from depressing the end, a portion of the stem directly ahead of the slot is raised relative to the remainder of the surface of the stem and relative to the contact edge. The raised portion directs the soil and debris away from the slot. The underside of the raised portion defines a retainer guiding and support channel which holds the wire end in the optimum sweep locking position and provides support for the wire to eliminate retainer deformation when high sweep removal forces are encountered during operation. The operator can clearly see if the sweep is properly wedged onto the sweep support by simply viewing the position of the wire end relative to the contact edge and the guiding and support channel.
In one embodiment of the sweep, a central portion just below the stem also includes a raised area to help direct material away from the stem to improve stem life and assist in reducing wear in the slot area and in the end of the retainer.
These and other objects, features and advantages of the present invention will become apparent to one skilled in the art upon reading the following detailed description in view of the drawings.